6.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Breno Leitao leitao@debian.org
[ Upstream commit bf3624cf1c3708284c53ed99a1c43f2e104dc2dd ]
The netdevsim driver was experiencing NOHZ tick-stop errors during packet transmission due to pending softirq work when calling napi_schedule(). This issue was observed when running the netconsole selftest, which triggered the following error message:
NOHZ tick-stop error: local softirq work is pending, handler #08!!!
To fix this issue, introduce a timer that schedules napi_schedule() from a timer context instead of calling it directly from the TX path.
Create an hrtimer for each queue and kick it from the TX path, which then schedules napi_schedule() from the timer context.
Suggested-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Breno Leitao leitao@debian.org Link: https://patch.msgid.link/20250219-netdevsim-v3-1-811e2b8abc4c@debian.org Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/netdevsim/netdev.c | 21 ++++++++++++++++++++- drivers/net/netdevsim/netdevsim.h | 1 + 2 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c index 42f247cbdceec..e4c0d77849b82 100644 --- a/drivers/net/netdevsim/netdev.c +++ b/drivers/net/netdevsim/netdev.c @@ -87,7 +87,8 @@ static netdev_tx_t nsim_start_xmit(struct sk_buff *skb, struct net_device *dev) if (unlikely(nsim_forward_skb(peer_dev, skb, rq) == NET_RX_DROP)) goto out_drop_cnt;
- napi_schedule(&rq->napi); + if (!hrtimer_active(&rq->napi_timer)) + hrtimer_start(&rq->napi_timer, us_to_ktime(5), HRTIMER_MODE_REL);
rcu_read_unlock(); u64_stats_update_begin(&ns->syncp); @@ -426,6 +427,22 @@ static int nsim_init_napi(struct netdevsim *ns) return err; }
+static enum hrtimer_restart nsim_napi_schedule(struct hrtimer *timer) +{ + struct nsim_rq *rq; + + rq = container_of(timer, struct nsim_rq, napi_timer); + napi_schedule(&rq->napi); + + return HRTIMER_NORESTART; +} + +static void nsim_rq_timer_init(struct nsim_rq *rq) +{ + hrtimer_init(&rq->napi_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + rq->napi_timer.function = nsim_napi_schedule; +} + static void nsim_enable_napi(struct netdevsim *ns) { struct net_device *dev = ns->netdev; @@ -615,11 +632,13 @@ static struct nsim_rq *nsim_queue_alloc(void) return NULL;
skb_queue_head_init(&rq->skb_queue); + nsim_rq_timer_init(rq); return rq; }
static void nsim_queue_free(struct nsim_rq *rq) { + hrtimer_cancel(&rq->napi_timer); skb_queue_purge_reason(&rq->skb_queue, SKB_DROP_REASON_QUEUE_PURGE); kfree(rq); } diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h index 96d54c08043d3..e757f85ed8617 100644 --- a/drivers/net/netdevsim/netdevsim.h +++ b/drivers/net/netdevsim/netdevsim.h @@ -97,6 +97,7 @@ struct nsim_rq { struct napi_struct napi; struct sk_buff_head skb_queue; struct page_pool *page_pool; + struct hrtimer napi_timer; };
struct netdevsim {